Turbine clutches are used in torque converters as a type of lock-up clutch. Turbine clutches comprise a turbine and a pump in a typical torque converter assembly in which the assembly includes components and processes to engage the turbine and pump in lockup mode similar to the engagement of a separate lockup clutch used to bring the turbine and pump into a common rotation with an engine. Turbine clutches have the advantage of removing the separate lockup clutch from the torque converter assembly which allows for reduced space requirements for the torque converter. In addition, costs are lowered as fewer components are needed and fewer assembly steps are required to assemble the torque converter.
However, it has been found that utilizing the pump as a component of a turbine clutch puts excessive strain on the pump shell itself, especially proximate to the edge of an inner shoulder of the pump impeller. In addition, because the edge of the pump facing the turbine is typically much smaller than the friction bearing surface of a separate lockup clutch, there is less surface area to hold the friction material that can be used for clutch engagement.
U.S. Pat. No. 6,406,262 to Kundermann addresses the issue of holding the vanes of the pump impeller in place using a retaining ring. However, Kundermann fails to address the strain places on an impeller while is in a lockup engagement with a turbine. In addition, Kundermann makes no specific mention of a turbine clutch or the effects of the turbine clutch on the impeller itself.
Thus, there is a need in the field for a component or method that relieves the strain placed on the impeller of a torque converter arranged to include the turbine-impeller engagement features found in a turbine clutch.